This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Alastin is a newly identified GTP-dependent membrane fusogen. It is an ~60 kDa integral membrane protein with two transmembrane domains near its C-terminus. Atlastin drives homotypic endoplasmic reticulum fusion in vitro and in vivo. We have recently reconstituted atlastin-mediated fusion with recombinant protein and proteoliposomes [Orso et al, Nature, 2009, 460(7258):978-83].